The present invention relates to cleaning means for a transported magnetic tape and, more particularly, to improved means for removing foreign material from the oxide-covered surface of the magnetic tape.
In using magnetic tape for storing signals to be utilized by a digital machine, and particularly a computer, it is necessary to transport the tape rapidly but in close proximity to the read/write transducers, termed heads, which detect or induce flux reversals in the tape surface. In order to accomplish this it is necessary that the tape not be spaced too far from the surface of the head, in which case the lines of flux emanating from the tape surface will be too weak to be accurately detected by the heads.
Previous tape machines, i.e. those operating at a rate of 3200 flux reversals per inch (f.r.p.i.) have been able to withstand transient head-to-tape separations up to 200 microinches due to foreign substances from the tape surface build up upon the heads. To combat this problem various tape cleaning devices have been devised, primarily including mechanical scraping devices for physically separating foreign matter from the surface of the tape.
With the advent of modern, high-density digital machinery, which commonly utilize a tape separation distance of approximately 70 microinches, the problem of foreign material upon tape surfaces has become particularly critical. In particular, prior art tape cleaning apparatus are not satisfactory for use with the more sensitive, modern equipment. Small foreign particles on the tape surface, which heretofore would not have been large enough to cause errors, will cause substantial errors when present on tapes of the high density variety. In addition, prior art cleaning apparatus do not remove soft particles or viscous materials from the surface very effectively. Still further, the previously used cleaning devices tend to accumulate foreign matter thereon which is from time to time transferred to the tape surface in relatively large amounts. Or the collected material can cause the tape to stick to the head and/or cleaner causing either a "no tape motion" condition, or pull out of the oxide from the tape.
It is therefore an object of the present invention to provide an improved apparatus for removing foreign matter from the surface of a transported magnetic tape.
It is another object of the present invention to provide an improved tape cleaning means which removes smaller particles than cleaners heretofore known.
Still another object of the invention is to provide an improved tape cleaning apparatus which is particularly well adapted to remove viscous materials from the surface of the tape.